Insulation for water cooled pipes in a reheating furnace

ABSTRACT

A fibrous ceramic insulating blanket is wrapped around the water-cooled pipes in a steel processing reheating furnace. The resilient blanket, in sections, is pressed onto threaded anchor studs projecting from the pipes and is held in place by ceramic anchors placed over each stud and secured to the stud by a lock nut. A ceramic mortar covers the lock nut seated in a depression in the ceramic anchor. The assembly is then sprayed overall with a liquid rigidizer which upon hardening provides a relatively hard and erosion resistant outer layer over a resilient inner layer.

United States Patent [191 Boto et a1.

[ INSULATION FOR WATER-COOLED PIPES IN A REHEATING FURNACE [75]Inventors: Louis Boto; David B. Rodger, both of Baytown, Tex.

[73] Assignee: United States Steel Corporation, Pittsburgh, Pa.

221 Filed: Dec. 20, 1972 21 App1.No.:316,938

[52] U.S. Cl 432/234, 138/149, 138/145,

432/246, 432/236, 117/169 A [51] Int. Cl. F2711 13/06, F27d 3/02 [58]Field of Search 432/233236,

3,329,414 7/1967 Greaney 432/234 [11] 3,20,947 June 28, 1974 3,451,6616/1969 Barker 432/234 3,486,533 12/1969 Doherty et a] 432/234 3,522,1137/1970 Kohler 117/169 A 3,561,494 2/1971 Hackett 138/145 3,647,1943/1972 Brungraber et al 432/234 3,666,555 5/1972 Jones 117/169 A3,687,093 8/1972 Byrd, .lr 110/] A 3,729,337 4/1973 Bearden et a1 117/169 A 3,781,167 12/1973 Ahonen 432/234 Primary Examiner-John J. CambyAssistant Examiner-Henry C. Yuen Attorney, Agent, or FirmRea C. Helm 57] ABSTRACT A fibrous ceramic insulating blanket is wrapped around thewater-cooled pipes in a steel processing reheating furnace. Theresilient blanket, in sections, is pressed onto threaded anchor studsprojecting from the pipes and is held in place by ceramic anchors placedover each stud and secured to the stud by a lock nut. A ceramic mortarcovers the lock nut seated in a depression in the ceramic anchor. Theassembly is then sprayed overall with a liquid rigidizer which uponhardening provides a relatively hard and erosion resistant outer layerover a resilient inner layer.

6 Claims, 8 Drawing Figures PATENTEDJUHZB I974 SHEET 1 0F 4 FIG. 2

PATENTED JUN 28 1974 SHEET 3 BF 4 PATENTEDJUHZB i974 SHEEI t Of 4 FIG. 7

INSULATION FOR WATER-COOLED PIPES IN A REHEATING FURNACE This inventionrelates to skid rail systems in steel pro cessing reheat furnaces andmore particularly to the insulation of the skid rail system members fromthe high temperatures of the reheating process.

In the processing of steel, ingots are rolled into shapes such as bloomsor slabs and subsequently heated again in reheating furnaces for furtherrolling. In conventional reheating furnaces the slabs or blooms to bereheated are pushed through the furnace on horizontal skid rails held inspaced relationship by transverse members. This structure is in turnsupported by vertical supports in such a manner that heating may takeplace on both the top and bottom of the slab or bloom. The supportingmember for the skids, the transverse members and the vertical supportsare water-cooled pipes. These pipes must be insulated to preventabsorption of too much of the heat supplied to the furnace.

Typically, this insulation is a rigid-preformed or cast refractorymaterial placed around the skid support pipe, the vertical supports andthe transverse members as shown, for example, in Corriston, US. Pat. No.2,022,649 or Greaney, US. Pat. No. 3,329,414 or the preformed refractorymaterial may be combined with resilient layers as shown in Barker, US.Pat. No. 3,45 1,661. However, pushing slabs or blooms along the skidsduring the heating process, causes the skids to flex and also createsvibrational shocks between the slabs and skids. The effect of the shocksand the flexing is the premature breaking away of the rigid preformed orcast refractories thereby exposing the pipes to destructive high heat.This results in excessive fuel consumption and additional costs toreplace insulation before the normal expected life of the refractory.

In accordance with our invention a fibrous ceramic insulating blanket iswrapped completely around the supporting and transverse pipes andpartially around the skid rail support pipes and pressed into a seriesof threaded alloy studs projecting outwardly from the pipes. Arefractory anchor is inserted over each stud and held in place by a locknut which is covered by a layer of high temperature mortar. The entireassembly is then sprayed with a rigidizer providing an insulationresistant to destruction from vibration and chatter, eliminating theproblems of high fuel consumption and repair costs.

It is therefore an object of our invention to provide an insulation forwater-cooled pipes in a reheating furnace that is resistant to damage ordestruction caused by vibrations.

Another object is to provide such insulation that is simple to installand reduces fuel and maintenance costs.

These and other objects will become more apparent after referring to thefollowing specification and drawings, in which:

FIG. 1 is a fragmentary perspective view of a reheating furnace showingthe conventional arrangement of skid rails, transverse members andsupporting members;

FIG. 2 is a plan view of part of the structure showing the insulation;

FIG. 3 is an enlarged elevation of a portion of a vertical supportmember;

FIG. 4 is a sectional view taken along line IIIIIl of FIG. 3;

FIG. 5 is an enlarged elevation ofa portion ofa transverse member;

FIG. 6 is a sectional view taken along line VV of FIG. 5;

FIG. 7 is an enlarged elevation of a portion of a skid member; and

FIG. 8 is a sectional view taken along line VII-Vll of FIG. 7.

Referring now to FIG. I, reference numeral 2 indicates the wall andreference numeral 4, the floor of a reheat furnace. Projecting upwardlyfrom floor 4 is a series of vertical supports 6, supporting transversemembers 8. Slabs S move on a series of parallel skid rails 10 supportedon pipes 12 which are in turn supported on transverse members 8. This isa conventional reheating furnace.

Referring now to FIGS. 3 and 4, vertical suppo member 6 includes a steelpipe 14 which may be about 3 inches in diameter with about Veto 34-inchwall thickness. Threaded Ar-inch alloy steel anchor studs 16, about 1%inch long are welded to pipe 14 in pairs, projecting opposite each otherfrom the circumference of the pipe, at about 1 foot intervals along thepipe. A I k inch thick alumina silica fibrous refractory blanket 18,such as Fiberfrax H manufactured by The Carborundum Company, is wrappedcompletely around pipe 14 in two foot lengths with the section endsbutted to gether. Although FIG. 3 shows a joint 20 between two sectionsof blanket at the same location as a pair of studs 16, joint 20 may belocated without regard to stud locations. It is preferred, however, tolocate a joint 22, also a butt joint, between the two ends ofa singlesection of blanket at a stud 16. A refractory anchor 24, about 2 inchesin diameter and about I inch long with a hole 26 to accommodate the studis placed on each stud 16. An alloy steel lock nut 28 secures the anchorto the stud, the nut fits into a protective recess 30 in the outer endof anchor 24. Anchor 24 may be made of a high alumina castablerefractory, a high duty fire brick. Blanket I8 is compressible, and whenlock nut 28 is fully seated, a slight dimple 32 is made in blanket 18.After nut 28 is secured, it is covered by a quantity of a ceramic mortar34 sufficient to protect nut 28 from the heat. Mortar 34 may be aMultiplex High Alumina Castable Refractory manufactured by the ChicagoFire Brick Company. The entire installation is then sprayed with arigidizer, a water soluble silicate such as an alkali silicate of thetype known as Fiberfrax Rigidizer manufactured by The CarborundumCompany, for the blanket insulation 18. The rigidizer is a liquid binderwhich, upon drying, increases the hardness and erosion resistance of theblanket. The rigidizer contains silica and penetrates about half way 36through blanket 18.

Referring now to FIGS. 5 and 6, pipe 38 of transverse member 8 may beabout 5 inches in diameter with about /ato 54-inch wall thickness.Blanket 18 is attached in the same manner as on vertical supports 6.Joint 22 is conveniently placed on the bottom of pipe 38 and a bottomrow of studs 16 on pipe 38 preferably has a stud located at each jointbetween each two foot long blanket section and an additional stud spacedbe tween the studs located at the joints. An additional row of studs isplaced on each side of pipe 38 spaced to provide two studs on each sidefor each "two foot long section of blanket 18.

FIGS. 7 and 8 show a similar insulation procedure for the insulationsurrounding pipe 12 which supports skid rail 10. Pipe 12 may be about 4inches in diameter and about /sto /i-inch thick. A row of studs 16 isplaced on each side of pipe 12 with an anchor on each side at each joint20 (FIG. 2) between sections of blankets t8, and an additional stud ineach row spaced between the studs located at the joints. Blanket 18 isnot wrapped entirely around pipe 12, but is spaced away from skid rail10 a sufficient distance so that a slab moving along rail 10 will notcontact the ends 40 of blanket 18.

The rigidizer is preferably applied after all the insulation blanket 18has been applied to all the pipes 12, 1.4 and 38. The insulationinstalled as described provid s a long lasting insulation resulting inlower material and replacement labor costs and fuel consumption than therigid type insulation because there is sufficient resiliency to resistdestructive vibration caused by movement of slabs along the skid rails.

We claim:

1. Vibration resistant insulation for water cooled members of a skidrail system in a reheating furnace comprising a plurality of permeableresilient fibrous aluminasilica blanket sections wrapped around thewater cooled members in abutting relationship,

means attached to said members for holding said blanket sections inplace around said members; and

a ceramic rigidizer applied to the outside of said blanket sectionswhile held in place around said members and penetrating partially intothe blanket sections thereby providing a rigidized outer layer and aresilient inner layer.

2. Insulation according to claim 1 in which the rigidizer is applied toeffect about half the thickness of the blanket sections.

3. Insulation according to claim 1 in which the means for holding saidblanket sections in place around said water cooled members includes aplurality of threaded studs attached to the members and projectingoutwardly through the blanket sections,

a refractory anchor adapted to fit over each stud for holding theblanket sections in place while slightly compressing the blanket sectionadjacent the anchor,

a lock nut for holding each anchor onto a stud,

a recess in each anchor for receiving the lock nut below the outersurface of the anchor with the end of the stud being below the outersurface of the anchor when the anchor is in position, and

ceramic mortar filling each recess thereby covering the lock nut andstud end.

4. Insulation according to claim 3 in which the rigidizer is applied toeffect about half the thickness of the nlanket sections.

5. Insulation according to claim 4 in which the refractory anchor andceramic mortar are each a high alumina castable refractory.

6. Insulation according to claim 5 which includes one of said studs ateach blanket section joint.

1. Vibration resistant insulation for water cooled members of a skid rail system in a reheating furnace comprising a plurality of permeable resilient fibrous alumina-silica blanket sections wrapped around the water cooled members in abutting relationship, means attached to said members for holding said blanket sections in place around said members; and a ceramic rigidizer applied to the outside of said blanket sections while held in place around said members and penetrating partially into the blanket sections thereby providing a rigidized outer layer and a resilient inner layer.
 2. Insulation according to claim 1 in which the rigidizer is applied to effect about half the thickness of the blanket sections.
 3. Insulation according to claim 1 in which the means for holding said blanket sections in place around said water cooled members includes a plurality of threaded studs attached to the members and projecting outwardly through the blanket sections, a refractory anchor adapted to fit over each stud for holding the blanket sections in place while slightly compressing the blanket section adjacent the anchor, a lock nut for holding each anchor onto a stud, a recess in each anchor for receiving the lock nut below the outer surface of the anchor with the end of the stud being below the outer surface of the anchor when the anchor is in position, and ceramic mortar filling each recess thereby covering the lock nut and stud end.
 4. Insulation according to claim 3 in which the rigidizer is applied to effect about half the thickness of the blanket sections.
 5. Insulation according to claim 4 in which the refractory anchor and ceramic mortar are each a high alumina castable refractory.
 6. Insulation according to claim 5 which includes one of said studs at each blanket section joint. 